Practice question

Plastic constitutes most persistent marine debris by item count in many surveys because production and disposal volumes are enormous, buoyant products travel far, and polymers degrade very slowly. Bags, bottles, fishing gear, packaging, and fragments remain in coastal and open-ocean systems for years. Glass and metal also occur but are generally less abundant and may sink or corrode; organic waste decomposes much more readily. Laboratory effects must be interpreted alongside environmentally realistic concentrations, while field detection demonstrates exposure but does not alone prove causation. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles. Because conventional polymers persist, fragmentation redistributes plastic into smaller pieces rather than removing its mass from the ecosystem. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing.